Clontarf's David McMurtry owns 36pc of UK-listed specialist engineering firm Renishaw, which makes precision measuring instruments and top-secret stuff for inside of iPhones. His stake is worth €650m, but shares have fallen sharply over the last year. McMurtry takes huge dividends from the company, getting €87m since 2009.
The 76-year-old spent €40m to build a futuristic eco house in Gloucestershire, which was used in the BBC hit drama Sherlock starring Benedict Cumberbatch. But McMurtry's wife Terry didn't like the house - which features 10 floors, an indoor bowling alley and an enclosed winter garden - so they live in a nearby converted barn.